Image forming apparatus, a toner counter and a calculation method of toner consumption

Abstract

Based on a video signal, a toner dot counter and an off dot counter detect a size of a toner dot portion to carry an adherent toner thereto and a size of an off dot portion not to carry an adherent toner, respectively. Reference is made to a look-up table based on the detection results, so as to retrieve a coefficient Kv corresponding to a combination of the sizes of the toner dot portion and the off dot portion. A count value Cdot given by the toner dot counter is multiplied by the coefficient Kv, while the resultant product is integrated by an accumulator. An integration value for an image of one page is multiplied by a coefficient K0 equivalent to a toner adhesion percentage of solid image. Thus is determined a toner consumption TC on the page image.

1. An image forming apparatus comprising:
 an image forming unit which forms a toner image by visualizing an electrostatic latent image with a toner; and 
 a toner-consumption calculator which calculates an amount of toner consumed by the image forming unit by integration of toner consumption for forming each toner dot portion which is a sub-assembly of consecutive toner dots included in the electrostatic latent image and distant from the other toner dot portions and to which the toner is made to adhere, 
 wherein the toner-consumption calculator calculates the toner consumption for forming each toner dot portion based on a size of each toner dot portion and a toner adhesion characteristic which is determined previously and represents a toner adhesion amount corresponding to each of sizes of toner dot portions. 
 
   
   
     2. An image forming apparatus according to  claim 1 , wherein the toner-consumption calculator calculates the amount of toner consumed for visualizing the toner dot portion by multiplying a value of dot information on the size of the toner dot portion by a coefficient defined based on the value of dot information and the toner adhesion characteristic. 
   
   
     3. An image forming apparatus according to  claim 2 , wherein the image forming unit comprises a latent image carrier which has its surface formed from a photosensitive material so as to be capable of carrying thereon the electrostatic latent image, and an exposure unit which irradiates a light beam on the surface of the latent image carrier, and forms the electrostatic latent image on the surface of the latent image carrier by scanning the light beam on a region of the surface of the latent image carrier that corresponds to the toner dot portion, and
 wherein the dot information represents an irradiation time of the light beam irradiated from the exposure unit onto a region of the latent image carrier corresponding to the toner dot portion. 
 
   
   
     4. An image forming apparatus according to  claim 2 , further comprising a signal processor which generates a multivalued signal relating to a toner dot portion to be formed by processing an image signal, and outputs the multivalued signal to the image forming unit,
 wherein the dot information is represented by the multivalued signal corresponding to the toner dot portion. 
 
   
   
     5. An image forming apparatus according to  claim 2 , wherein the toner-consumption calculator classifies the size of the toner dot portion into plural groups and defines the coefficient to each group respectively, and the sizes are finely classified in a region where the toner adhesion characteristic varies relatively greatly but are roughly classified in a region where the toner adhesion characteristic varies less. 
   
   
     6. An image forming apparatus according to  claim 1 , wherein the image forming unit comprises a latent image carrier capable of carrying thereon the electrostatic latent image, and a toner carrier disposed in face-to-face relation with the latent image carrier via a predetermined gap therebetween and carrying the toner on its surface, and forms the toner image by transferring the toner from the toner carrier to the latent image carrier. 
   
   
     7. An image forming apparatus according to  claim 1 , wherein the toner-consumption calculator integrates a toner consumption on each of the toner dot portions visualized by the image forming unit during a predetermined time period, and thereby calculates an amount of toner consumed during the time period. 
   
   
     8. An image forming apparatus according to  claim 7 , wherein the amount of toner consumed by the apparatus during the time period is calculated by adding an offset value based on use conditions of the apparatus to the integration value. 
   
   
     9. An image forming apparatus comprising:
 an image forming unit which forms a toner image by visualizing an electrostatic latent image with a toner; and 
 a toner-consumption calculator which calculates an amount of toner consumed by the image forming unit by integration of toner consumption for forming each toner dot portion which is a subassembly of consecutive toner dots included in the electrostatic latent image and distant from the other toner dot portions and to which the toner is made to adhere, 
 wherein the toner-consumption calculator calculates an amount of toner consumed for forming each toner dot portion by multiplying a value of dot information corresponding to a size of the toner dot portion by a predetermined coefficient, and 
 wherein the coefficient is defined based on a previously determined relation between a size of a toner dot portion and a toner adhesion amount to the toner dot portion and according to the dot information. 
 
   
   
     10. An image forming apparatus according to  claim 9 , wherein the image forming unit comprises a latent image carrier which has its surface formed from a photosensitive material so as to be capable of carrying thereon the electrostatic latent image, and an exposure unit which irradiates a light beam on the surface of the latent image carrier, and forms the electrostatic latent image on the surface of the latent image carrier by scanning the light beam on a region of the surface of the latent image carrier that corresponds to the toner dot portion, and
 wherein the dot information represents an irradiation time of the light beam irradiated from the exposure unit onto a region of the latent image carrier corresponding to the toner dot portion. 
 
   
   
     11. An image forming apparatus according to  claim 9 , further comprising a signal processor which generates a multivalued signal relating to a toner dot portion to be formed by processing an image signal, and outputs the multivalued signal to the image forming unit,
 wherein the dot information is represented by the multivalued signal corresponding to the toner dot portion.